i bite my nails all the time too, but i think that so many people do that, it shouldn't be called a bad habit.. it should be a normal habit..

i crack my knuckles A LOT! and that annoys a lotta people...

Also, i am NONSTOP touching my hair, i pull apart my split ends which is super bad for your hair and when i'm not doing that, i'm just running my fingers thru it constantly...

wow ok, i have a LOT of bad habits...